Systema M160 Spring

[Mantelope]

Take a look at the spring comparison chart: http://www.arniesairsoft.co.uk/?filn...ring_guide.htm
You'll notice that the M130 isn't even on there, which means you're going to be putting out more than 450FPS. If you play with that and you hit someone, they're going to be hurt and probably call you on it. The game organizer will chrono your gun, and you will probably be ejected from the game for knowingly upgrading WAY beyond the limits.

[[]D[][]\/[][]D]

So I guess it'll be an M120 then. Thanks harleyb for that link on the list.

[ILLusion]

putting that much power into a short barreled gun is too expensive and not cost effective. A LOT of power efficiency is lost in the short barrel.

Case in point:
Not too long ago, I was upgrading an AK beta spetz with a stock bore inner barrel (229mm long). These springs all returned velocities very close to each other (around 340-370fps):
Systema M100, M120, M120S, Prometheus MS100SP, MS110SP, PDI 140%, 150%, 170% & a Guarder SP110.

The target velocity was 400fps

I was almost certain that the barrel length was the cause.

So as a test, I installed a 6.03mm tightbore inner barrel that I believe was M4 Length (363mm) and the velocities instantly jumped up with the Systema M120S shooting a high of 425fps. That was almost a 60fps increase.

If we were to continue to keep upgrading until we were able to reach 400fps with the original barrel, the costs involved would have been ridiculously high, and not cost effective.

If you're looking for ~400fps, a Prometheus MS110SP-MS120SP or Systema M120, a spring guide that has bearings, a piston head with bearings and a 6.03mm inner barrel will get you there with very consistent velocity results. Even better if you can get a longer inner barrel covered with a suppressor to make the system more efficient.

In a sig 552, your battery solutions are extremely limited and you'll need to get a torque up gear set to handle the M120. You'll need to go up ANOTHER torque up gear level just to handle an M130... which means more money. As well, you'll need to upgrade your piston to keep it from dying prematurely and killing your gears.

Because of your battery limitations, your rate of fire will be severely compromised at these power levels.

[Greylocks]

Droc, I meant his original idea of an M160.

My suggestion for the Sig; M100 or equivalent. Bearing guide. Bushings. Better piston set, possibly better gear set.

Be sure to have the skills to put it all together. Remember that 400fps in most places is an UPPER limit, not a Goal to reach at all costs.